Risk Assessment of Elodea nuttallii – submission for consideration of Union listing under EU IAS Regulation No. 1143/2014 Name of Organism: Elodea nuttallii (Planch.) St. John – Nuttall’s pondweed Assess the risks associated with this species for Union listing under EU Objective: Regulation No. 1143/2014 Version: EU amendmed template for submission February, 2016. Version 1.2.1 Author(s) IRELAND - Michael Millane, Joe Caffrey, Colette O’Flynn Expert reviewers Catherine McGavigan, Melanie Josefsson EU Chapeau Stage 1 - Organism Information Stage 2 - Detailed Assessment Section A - Entry Section E – Risk Summaries and Conclusion Section B - Establishment Section F - Additional Questions Section C - Spread Section D - Impact References About the risk assessment This risk assessment is based on the Non-native species APplication based Risk Analysis for Ireland (NAPRA Ireland) tool (version 2.66) and the EU Non-native Organism Risk Assessment Scheme template. Quality assurance procedure In 2014, the NAPRA Ireland version of this risk assessment was drafted and then internally reviewed by an Inland Fisheries Ireland aquatic invasive species expert. This was then reviewed by an external third party expert. The final draft version was then made widely available for key stakeholder and general public consultation through a series of open meetings and online consultation. All consultation comments were documented and then reviewed by the external expert. The final NAPRA Ireland version was published online on 15/09/2014 and is accessible from: http://nonnativespecies.ie. Prior to initial submission for its consideration as a species of Union concern, an EU Chapeau and inclusion of reference to ecosystem services added. This was reviewed by Dr. Joe Caffrey. In consideration of initial comments received by the Scientific Forum, the risk assessment questions have been revised to focus at the European level. This revised version has been kindly reviewed by Melanie Josefsson (Swedish Environmental Protection Agency). Notes: Confidence is rated as low, medium, high or very high. Likelihood is rated as very unlikely, unlikely, moderately likely, likely or very likely. Magnitude of risk is rated as Minimal, Minor, Moderate, Major and Massive The percentage categories are 0% - 10%, 11% - 33%, 34% - 67%, 68% - 90% or 91% - 100%. N/A = not applicable. Page 1 of 29 DOCUMENT CONTROL SHEET Version Control Table Version No. Status Authors(s) Reviewed by Approved by Date of issue Draft 1 Complete Dr Michael Millane Dr Joe Caffrey 21/03/2014 Dr Catherine Expert review Complete Dr Michael Millane Dr Joe Caffrey 11/02/2014 McGavigan Public Complete Dr Michael Millane Dr Joe Caffrey 09/05/2014 Consultation 1 Public Complete Dr Michael Millane Dr Joe Caffrey 14/08/2014 Consultation 2 Dr Cathal Final Complete Dr Michael Millane Dr Joe Caffrey 15/09/2014 Gallagher NAPRA EU Final Colette O’Flynn Dr Joe Caffrey 30/11/2015 amendments NAPRA EU Complete Colette O’Flynn Melanie Ferdia Marnell, 29/02/2016 Re-submission Josefsson National Parks and Wildlife Service, Ireland Page 2 of 29 EU CHAPPEAU QUESTION RESPONSE 1. In how many EU member states has this species been recorded? List them. 20 countries: Austria, Belgium, Bulgaria, Croatia, Czech Republic, Denmark, Estonia, France, Germany, Hungary, Ireland, Italy, Luxembourg, Netherlands, Poland, Romania, Slovakia, Slovenia, Sweden, United Kingdom (DAISIE 2016; GBIF 2015; Josefsson 2011). 2. In how many EU member states has this species currently established 17 countries: Austria, Belgium, Bulgaria, Denmark, France, Germany, Hungary, Ireland, Italy, populations? List them. Luxembourg, Netherlands, Poland, Romania, Slovakia, Slovenia, Sweden, United Kingdom (DAISIE 2016, GBIF 2015). 3. In how many EU member states has this species shown signs of 9 countries: Belgium, Bulgaria, Denmark, France, Ireland, Netherlands, Poland, Sweden, invasiveness? List them. United Kingdom (EPPO 2002; Gederaas et al. 2012; NOBANIS 2016; Petrova et al. 2013) 4. In which EU Biogeographic areas could this species establish? Atlantic, Boreal, Continental, Pannonian and lower parts of the Alpine (Biogeographic Areas in Europe, 2011. European Environment Agency see: http://www.eea.europa.eu/data-and- maps/figures/biogeographical-regions-in-europe-1) 5. In how many EU Member States could this species establish in the future 28 countries: Austria, Belgium, Bulgaria, Cyprus, Croatia, Czech Republic, Denmark, Estonia, [given current climate] (including those where it is already established)? List Finland, France, Germany, Greece, Hungary, Ireland, Italy, Latvia, Lithuania, Luxembourg, them. Malta, Netherlands, Poland, Portugal, Romania, Slovakia, Slovenia, Spain, Sweden, United Kingdom. Its current absence from Southern Europe (except southern France) may indicate that the environmental conditions of the Mediterranean biogeographic region may be limiting factors to its establishment (see response to Question 6 below). 6. In how many EU member states could this species become invasive in the 8 countries: Croatia, Czech Republic, Estonia, Finland, Latvia, Lithuania, Portugal, Spain. future [given current climate] (where it is not already established)? While Elodea nuttallii has a high tolerance to wide ranges of environmental conditions (Zehnsdorf, 2015) and can establish in a wide range of freshwater habitats (and slightly saline habitats), it has a preference for temperate or continental climates that are wet year round (Duenas, 2013). This may inhibit its potential to be invasive in Cyprus, Greece and Malta. Page 3 of 29 Stage 1 - Organism Information The aim of this section is to gather basic information about the organism. N QUESTION RESPONSE COMMENT 1 Identify the organism. Is it clearly a single This risk assessment is for Elodea nuttallii (Planch.) St John taxonomic entity and can it be adequately Synonyms: Anacharis occidentalis (Pursh) St. John, Anacharis nuttallii distinguished from other entities of the same Planchon, Elodea columbiana St. John,, Elodea minor Farw., Anacharis rank? occidentalis (Pursh) Marie-Victorin, Serpicula occidentalis Pursh, Elodea canadensis var. angustifolia (Britton ex Rydb.) Farw. (DAISIE 2016, and Simpson and Duenas 2011). Common names: Aprólevelű átokhínár – Hungarian, Élodée à feuilles étroites – French, Elodée de Nuttall – French, Nuttall's Waterweed – English, Nuttall's YES waterweed/pondweed – English, Nuttall-Wasserpest – German, Nuttalls Wasserpest – German, Nuttall’s pondweed – English, Peste d'acqua di Nuttall – Italian, Peste d’acqua di Nuttall – Italian, Schmalblättrige Wasserpest – German, Smalle waterpest – Dutch, Vodní mor americký – Czech, Western waterweed - English (DAISIE 2016 and Duenas 2013). Taxonomy: Plantae – Magnoliophyta – Liliopsida – Alismatales – Hydrocharitaceae – Elodea – Elodea nuttallii 2 If not a single taxonomic entity, can it be redefined? (if necessary use the response N\A box to re-define the organism and carry on) 3 Describe the organism. Elodea nuttallii is a perennial, submerged aquatic species that typically grows in muddy substrates in meso- or eutrophic waters in depths of 3 metres or less. However, the plant displays plastic characteristics and can grow more vigorously and to depths of up to 6 m in eutrophic waters. The plant can also form dense stands which can reach the water surface. Elodea nuttallii stems are long and slender and often branched. Upper leaves normally in whorls of 3, can be 4 (rarely 5) and the lower leaves may be in 2’s and opposite. The leaves have marginal teeth 0.05-0.1mm long, are widest at their base and tapering to a point, are mostly recurved, are usually folded along the midriff, and are 6-13mm long and 0.7–1.5 mm wide. Flowers are less than 8mm wide (Bowmer et al. 1995; Josefsson 2011; CAISIE 2013a). Elodea nuttallii is very similar and difficult to distinguish from Elodea canadensis. Elodea nuttallii is generally smaller and paler than Elodea canadensis, its leaves are generally shorter and narrower and its stalk is often more branched (Bowmer et al, 1984). Hybrids between Elodea canadensis and Elodea nuttallii may occur (Cook & Urmi-König, 1985). E. nuttallii can also be confused with Elodea callitrichoides which is present in Austria, France, Ireland and the UK. Elodea callitrichoides has leaves up to 25 mm Page 4 of 29 Stage 1 - Organism Information The aim of this section is to gather basic information about the organism. N QUESTION RESPONSE COMMENT long and 2-5 mm broad in whorls of three, Leaves are flat, spreading and have some straight margins (Bowmer et al.1995) Elodea nuttallii can also be mistakenly identified as Egeria densa, Hydrilla verticillata and Ceratophyllum sp. and may be in trade under these species names. Egeria densa has longer leaves in whorls of 4–6. Hydrilla verticillata has tubers and spiny leaf edges, Ceratophyllum has forked needle-like leaves. 4 Does a relevant earlier risk assessment No European level risk assessment exists for this species. However, many exist? (give details of any previous risk European countries including Belgium, United Kingdom, Ireland, Norway and assessment) No Poland have risk assessed this species at the national level (Branquart et al. 2010; GB Non-Native Species Secretariat 2011; Millane et al. 2014; Gederaas et al. 2012; Tokarska-Guzik B. et al. 2015). 5 If there is an earlier risk assessment is it still N/A entirely valid, or only partly valid? 6 Where is the organism native? Temperate regions of North America (USDA, ARS 2013). 7 What is the current global distribution